diff --git a/AlgebraicDataflowArchitectureModel/models/Citrus.model b/AlgebraicDataflowArchitectureModel/models/Citrus.model
index a4cd25b..356405a 100644
--- a/AlgebraicDataflowArchitectureModel/models/Citrus.model
+++ b/AlgebraicDataflowArchitectureModel/models/Citrus.model
@@ -19,18 +19,24 @@
 }
 
 channel DeleteBook(aid:Str) {
-	out accounts.{aid}.books(bookList:List, deleteBook(bid:int)) = if(bid < length(bookList), remove(bookList, bid), bookList)
+	out accounts.{aid}.books(bookList:List, deleteBook(bid:Int)) = if(bid < length(bookList), remove(bookList, bid), bookList)
 }
 
 channel CreateToDo(aid:Str, bid:Int) {
-    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, createtodo(year:Str, month:Str, day:Str, title:Str)) = insert(toDoDB, 
-    																												year, 
-		                                                                                                        	insert(lookup(toDoDB, year), 
-		                                                                                                        			month, 
-	    	                                                                                                    			insert(lookup(lookup(toDoDB, year), month), 
-	    	                                                                                                    					day, 
-																																	append(lookup(lookup(lookup(toDoDB, year), month), day), 
-																																			{"title": title, "check": false}))))
+    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, createtodo(year:Str, month:Str, day:Str, title:Str)) = 
+    if(
+    	contains(toDoDB,year),
+    	if(
+    		contains(lookup(toDoDB,year),month),
+        	if(
+        		contains(lookup(lookup(toDoDB,year),month),day),
+            	insert(toDoDB,year,insert(lookup(toDoDB,year),month,insert(lookup(lookup(toDoDB,year),month),day,append(lookup(lookup(lookup(toDoDB,year),month),day),{"title":title,"check":false})))),
+            	insert(toDoDB,year,insert(lookup(toDoDB,year),month,insert(lookup(lookup(toDoDB,year),month),day,append(nil,{"title":title,"check":false}))))
+            ),
+        	insert(toDoDB,year,insert(lookup(toDoDB,year),month,insert(nil,day,append(nil,{"title":title,"check":false}))))
+        ),
+    	insert(toDoDB,year,insert(nil,month,insert(nil,day,append(nil,{"title":title,"check":false}))))
+    )
 }
 
 channel ChangeToDoName(aid:Str, bid:Int, year:Str, month:Str, day:Str, tid:Int) {
@@ -42,7 +48,7 @@
 }
 
 channel DeleteToDo(aid:Str, bid:Int) {
-    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, deleteToDo(year:Str, month:Str, day:Str, tid:int)) = insert(toDoDB, 
+    out accounts.{aid}.books.{bid}.todos(toDoDB:Map, deleteToDo(year:Str, month:Str, day:Str, tid:Int)) = insert(toDoDB, 
     																											year,
                                                                                                         		insert(lookup(toDoDB, year), 
                                                                                                         				month,